[swtbkim]

Hi all!

I am writing UDF for particle-laden flow across a pipe.

This is my criterion:
When the particle impacts on the pipe surface, if sum of some forces acting on the particle is larger than some criterion force, then particle will be trapped on the surface. If not, then reflected

Here, I want to calculate mass flux of trapped particles and save it into UDM,
in order to show where the particles are trapped more by showing the contour of the UDM

So this is basically similar with the example of DEFIEN_DPM_EROSION in UDF manual.

This is my code.

DEFINE_DPM_BC(bc,p,t,f,f_normal,dim)
{

//force calculation here//

if(F_net >= F_cr)
{
F_AREA(A,f,t);
area = NV_MAG(A);

c0 = F_C0(f,t);
t0 = THREAD_T0(t);
C_UDMI(c0,t0,0) = P_FLOW_RATE(p)/area;


return PATH_ABORT;
}
else
return PATH_ACTIVE;
}

Flow and other things converged well, but UDM kept increasing as iterating more.
This is weird because particle input is constant and DPM concentration at outlet also converged to a constant value.

I tried to use transient solver, and modify C_UDMI(c,t,0)=P_MASS(p)/CURRENT_TIME_STEP/AREA, but the result was similar, that is, C_UDMI kept increasing.


Why does this happen?
Do I need to reset UDM in this case?

Thank you.